Method and apparatus for forming valve bodies

ABSTRACT

A bottomed tubular blank or a blank having an open end and a closed end is formed into a valve body whose shape is defined by a pair of dies and the ends of pistons incorporated in the dies. Pressure oil is introduced into the blank through one of the pistons to bulge the blank to the shape thus defined. There are provided upper and lower pressing dies between which the blank is disposed and pistons extending into the dies in four directions, with the piston for pressing the opening of the blank being provided with an inlet for supplying the pressure oil into the blank and an outlet for discharging the pressure oil. When required, the blank is pressed by the dies for preliminary forming and then subjected to the hydraulic bulge forming.

United States Patent Tadokoro METHOD AND APPARATUS FOR FORMING VALVEBODIES [72] Inventor: Toyotoshi Tadokoro, Osaka, Japan [73] Assignee:Furubayashi Kogyo Kabushiki Kaisha, Osaka, Japan [22] Filed: April 21,1970 21 Appl. No.: 30,443

[30] Foreign Application Priority Data 1451 Aug. 8, 1972 3,350,905 11/1967 Ogura et al ..72/62 Primary Examiner-Richard J. HerbstAtt0rney-Holman & Stem ABSTRACT A bottomed tubular blank or a blankhaving an open end and a closed end is formed into a valve body whoseshape is defined by a pair of dies and the ends of pistons incorporatedin the dies. Pressure oil is introduced into the blank through one ofthe pistons to bulge the blank to the shape thus defined. There areprovided upper and lower pressing dies between which the blank isdisposed and pistons extending into the dies in four directions, withthe piston for pressing the opening of the blank being provided with aninlet for supplying the pressure oil into the blank and an outlet fordischarging the pressure oil. When required, the blank is pressed by thedies for preliminary forming and then subjected to the hydraulic bulgeforming.

9 Claims, 19 Drawing Figures P'ATENTED nus 8 m2 3 6 8 1. 96 0 sum a nr 3METHOD AND APPARATUS FOR FORMING VALVE BODIES BACKGROUND OF THEINVENTION The present invention relates to a method and apparatus forforming bottomed tubular blanks into valve bodies.

As substitutes for conventional valve bodies made of cast iron or steel,seamless valve bodies have already been produced from a length ofseamless pipes by hydraulic bulge forming, and methods and apparatusesfor this purpose are known. In forming a tubular blank into a valvebody, a portion of the blank has to be bulged markedly in order to formthe main part of the valve body for housing a valve disk and a valveseat. Accordingly, the valve body produced by conventional methods has athin wall at the bulged portion, so that it has been impossible toobtain valve bodies of high strength because those heretofore producedare not satisfactory in rigidity which is strictly essential to theproduct. Furthermore, valve bodies whose main portions are bulged to anextreme extent by the foregoing method are by no means employable inpractical use.

The present invention has accomplished improvements over conventionalmethods for producing valve bodies and provides valve bodies with auniform wall thickness so as to impart a high rigidity to the valvebodies even when the products include main parts bulged to a greatextent.

SUMMARY OF THE INVENTION An object of the present invention is to form abottomed tubular blank into a valve body by hydraulic bulge forming soas to provide the main part of the valve body with a small degree ofbulging for correction of irregularity in wall thickness of the product,with the valve body obtained thus being of a high rigidity and excellentresistance to corrosion and impact of fluid due to cavitation or thelike.

Another object of the present invention is to subject the blank to apreliminary forming by a pair of dies and then subsequently to theabove-mentioned bulge forming in the dies. In accordance with thismethod, valve bodies of a higher degree of deformation such as thoseprovided with slide valve guides or those of a modified sectional shapesuch as oval or rectangular shape can be readily formed with a uniformwall thickness. The present method is therefore very advantageous fromthe viewpoint of operation efficiency and maintenance of the dies.

The method of the present invention is practiced by an apparatuscomprising a pair of upper and lower dies provided with blank grippingportions for defining a horizontal passage, each of the dies beingprovided at its center portion with a bulging hole formed at arightangle with the blank gripping portion, a clamp press for clampingthe upper and lower dies provided with stopper pistons inserted into thebulging holes respectively, and pressing pistons extending into thepassage at its opposite ends, with one of the pressing pistons beingprovided with a pressure oil inlet and a pressure oil outlet extendingto the end surface thereof, and the other of the pressing pistons beingprovided with an end surface of a shape in conformity with the shape ofthe bottom of a product to be obtained.

Generally, a bottomed tubular blank is placed in the passage in clampingengagement with the upper and lower dies and the two stopper. pistonsare stopped at the desired positions. Pressure oil is introduced intothe blank by way of the pressing piston while the blank is being pressedby the two pressing pistons at the opposite sides thereof, so that theblank is bulged to the shape defined by the dies and each of thepistons. In the case where the dies are further provided with bulginggrooves for bulging the corresponding portions of the valve body instraight or annular shape, reinforcing ribs or portion for receiving aseat ring may simultaneously be formed at the desired position duringthe operation.

Moreover, where a valve body has to be produced by deforming a bottomedtube to a great extent because of the deformed section of the productsuch as an oval or rectangular shape, it is very difficult to obtain aproduct of high strength by hydraulic bulge fonning due to the variationin wall thickness of the product. In such instance, the blank placed inthe dies may be deformed by means of the dies to a shape resembling thevalve body to be obtained and then subjected to hydraulic bulge forming.The preworking thus effected makes it easier to produce valve bodies ofspecial shapes with satisfactory quality. In this case, a simultaneousprovision of slide valve guides in the valve bodies can be readilyachieved by modifying the form of the dies.

Further, by modifying the shape of end surface of the pressing cylinderfor defining the form of the blank, a seat for fixing a cock or the likecan be formed simultaneously in the bottom of the product. If the endportion of this pressing piston is so made as to be replaceable, theform of the end surface can be varied as desired by the replacement ofthe end portion.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view in sectionillustrating an apparatus for producing a valve body by the principalmethod of the present invention, the apparatus being shown as it is inoperation;

FIG. 2 is an exploded view and illustrates a method for producing atubular body with a bottom to be used as a blank in the presentinvention, (a) showing a tubular material before it is subjected toworking, (b) showing the tubular blank obtained;

FIG. 3 is an exploded view and shows typical forms of the bottomedtubular blank to be used in the present invention, (a) showing a tubularblank with a flat bottom, (b) showing a tubular blank with a bottom ofmodified form, the views illustrating the blank in section taken alongthe planes intersecting at the angle of FIG. 4 is an exploded view andshows the principal embodiments of pressing pistons, (a) illustrating apressing piston for introducing pressure oil into a blank, (b)illustrating another pressing piston for shaping the bottom of a valvebody;

FIG. 5 is a view in section showing a modified embodiment of a pair ofdies;

FIGS. 6 (a) and (b) show modified forms of the end of the pressingpiston for defining the bottom shape of a valve body;

FIG. 7 shows an example of the valve body produced by the apparatus inFIG. 1, (a) being a side elevation, (b) being a front view in verticalsection;

FIG. 8 is an exploded view and shows the form of the dies and deformedblanks obtained by preliminary pressing conducted prior to hydraulicbulge forming,

(a) showing a valvebody circular in section which is provided, inopposite sides, with ribs serving as reinforcements and slide valveguides, (b) showing a valve body oval in section which is provided, inits opposite sides, with ribs serving as reinforcements and slide valveguides, showing a valve body rectangular in section which is provided,in its opposite sides, with ribs serving as reinforcements and slidevalve guides;

FIGS. 9 (a), (b), and (c) are end views and sectional views showingvarious forms of the endof the pressing piston 'on one side to be usedfor bulge forming of the valve bodies which have sectional forms shownin FIGS. 8 (a), (b) and (c); and

FIG. 10 is a perspective view showing a slide valve made of a tubularblank having a circular form in'section shown in FIG. 8 (a).

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the embodimentshown in FIG. 1, designated at A is a pair of an upper die 1 and a lowerdie 2. Each of the dies 1 and 2 is provided with a blank grippingportion 4 for defining a horizontal passage 3 having openings atopposite ends and a bulging hole 5 formed in the center thereof at aright angle with the blank gripping portion 4. A clamp press B forpressing the upper and lower dies 1, 2 is provided with knockoutcylinders (not shown) for driving stopper pistons 6 into the bulgingholes 5 formed in the dies 1 and 2. A pressing piston 7 extends into thepassage 3 at one opening thereof and a second pressing piston 8 extendsinto the passage 3 at the other opening, with both pressing pistonsbeing so shaped in section as to be fitted into the passage 3. Thepressing piston 7 has an oil inlet 9 and an oil outlet 10 extending toits end surface 7a, while the pressing piston 8 has an end surface 8a inconformity with the form of bottom 11 of a product C to be formed.Designated at 12 is a distance piece attached detachably to the end ofthe pressing piston 8. The end surface 8a is formed at the front end ofthe distance piece 12. The distance piece 12 serves to change theposition of the end of piston 8 when the piston is advanced to thegreatest extent with a constant stroke and to modify the shape of theend surface 80. The pressing piston 7 is provided at its end with aportion 7b having a smaller diameter to be fitted into the mouth of ablank D and a stepped portion 70 to be brought into contact with edge13a of the mouth for oiltight contact with the blank D during thebulging operation. Oil ducts l4 and 15 communicate with the oil inlet 9and outlet 10 and are each provided with control values V and V Employedas the blank D is a tube closed at one end obtained by subjecting atubular article 16 to friction forming or hot spinning or a bottomedtube produced by plastic working such as forging or sheet metal working.The shape of the blank D is versatile as shown in FIG. 3 and is selecteddepending upon the shape of the valve body to be formed. The closed endmay be in flat shape as seen in FIG. 3 (a) or it may be of a modifiedform as shown in FIG. 3 (b). Although not shown, the blank D-may becircular, oval, or elliptical in section taken at a right angle to itsaxis. FIG. 2 shows a method of shaping the blank D by friction forming,in which one end 16a of a tube 16 is pressed against recessed portion17a of a die 17 with relative rotation being effected therebetween toproduce friction. The end 16a of the tube 16, while being guided andgathered together, is fused to a closed shape by the heat generatedwhereby the bottomed tubular blank D as shown in FIG. 2 (b) is obtained.

The blank D is placed between the gripping portions 4 of the upper die 1and lower die 2, which are then brought to clamping position by theclamp press B. The piston 7 and. the second piston 8 are thereafteradvanced to bring them into pressing contact with the blank D at theopposite sides, with the piston 7 being in oiltight contact with themouth 13 of the blank D within the passage 3. The control valve V forthe oil duct 14 and the control valve V for the oil duct 15 are openedto introduce pressure oil into the blank D through the inlet 9 and allowthe oil to flow into the oil duct 15 through the outlet 10 whereby airis driven out of the blank D. Then the control valve 15 is closed. Oilof higher pressure is introduced through the inlet 9 to bulge the blankD while the blank D is being subjected to horizontal pressure extertedthereon simultaneously by the pistons 7 and 8 actuated in operativerelationship with each other, with the result that the portions of theblank D which are positioned at the holes 5 are bulged into the holesuntil the portions are blocked by the stopper pistons 6 inserted in theholes 5. During this operation the bottom or closed end of the blank Dis brought into fitting contact with the end surface 8a of the piston 8.In this manner, a seamless valve body of the desired shape can be madeof the bottomed tubular blank D in one step of process.

In the case where annulargrooves 18 are formed along the edges of thebulging holes 5 in the gripping portions 4 of the upper and lower dies1, 2 as shown in FIG. 5, the corresponding portions of the blank D canbe bulged to the shape 19 in conformity with the annular grooves 18 asshown in imaginary lines in FIG. 7. The annular bulged portion 19 thusformed serves to reinforce the valve body and can be utilized as thespace for inserting a seat ring. Further grooves 21, when formed alongjunction lines 20 of the dies A, produce bulged portions 22 inconformity with the grooves 21 in the valve body as shown in imaginarylines in FIG. 7. The bulged portion 22 serves to reinforce the valvebody and serves as a guide when the valve body is employed as a slidevalve. The bulged portions above may be provided as desiredsimultaneously when the valve body is fonned. The product C shown inFIG. 7 is obtained by cutting off the end of portion 23 which is bulgedinto the hole 5. If a cavity 24 is formed in the end 8a of the piston 8as shown in FIG. 6 (a), a projection corresponding to this cavity isproduced in bottom 11 of the valve body. When it is required to attach acock or the like, the projection serves as a seat therefor. With the endsurface 8a shown in FIG. 6 (b), a valve body having a bottom shown inFIG. 7 is obtained. In accordance with the present method, the bottomedtubular blank D is formed into a valve body with a small degree ofdeformation, with the resultant advantages that the bulged portion has athick wall to insure desired regidity and strength against corrosion andshock impact due to cavitation of fluid or the like.

Depending upon the form of a valve body to be produced, the blank may besubjected to'a markedly great degree of deformation even with the use ofa bottomed tubular material. The present invention, when practiced inthe following manner, can be applied to such case with good results.

This method is employed in working a blank D which is not identical witha product C to be obtained in sectional shape taken at right angle withthe axis. Mainly used as the blank D is a material exactly circular insection which is easy to work. As a preliminary step of working, theblank D placed between the gripping portions 4 of the upper and lowerdies 1, 2 is deformed to a sectional shape identical with or similar tothat of the valve body to be produced by utilizing the clamping force ofthe press B. The deformation produced is illustrated in FIG. 8, in which(a) shows a mode of preworking for producing a product C approximatelycircular in section, FIG. 8 (b) showing another mode of preworking forforming a product C which is oval in section, and FIG. 8 (0) showingstill another mode of preworking for forming a product C which iselliptical in section. The blanks D indicated in imaginary lines inthese figures are all circular in section, while the preworked blanks Eare each provided at opposite sides, with ribs 25 serving asreinforcements and slide valve guides and formed simultaneously by thepreliminary working. Alternatively, the ribs may be provided by ahydraulic bulge forming to be described later. The upper die 1 indicatedin the dot-dash line in FIG. 8 shows the position prior to thepreworking. The preworked blank D may not necessarily be of a sectionalshape in conformity with the shape of passage 3 defined by the upper die1 and the lower die 2, but it may be in such shape as resembling theshape of the passage 3. In the case of the former, the outer diameter ofthe blank D may be such that the blank can be deformed to the sectionalshape of the passage 3 without objectionable results. Upon completion ofthe preworking, the pistons 7 and 8 are driven forward into pressingcontact with the blank D at its opposite sides while the upper and lowerdies 1, 2 are retained in clamping position by the press B. The piston 7is held in oiltight contact with the mouth 13 of the blank D within thepassage'3 and pressure oil is then introduced into the blank D. In thesame manner as in the foregoing embodiment, the blank D is bulged to theshape of a valve body to be obtained. This process assures formation ofthe desired valve body with extreme ease without producing a local thinwall portion even when the blank D is different from the valve body tobe obtained in sectional shape. Accordingly, instead of using a materialwhich is in a specific sectional shape such as in oval or ellipticalform, a material exactly circular in section and therefore easier towork can be used even in forming a valve body such as a slide valvewhich has a special shape.

Although it is possible to carry out this method by using pressingpistons similar to those in the previously described method, anotherembodiment of the pressing piston 7 is shown in FIG. 9. The pressingpiston 7, so shaped in section as to fit in the passage 3 defined by theupper die 1 and the lower die 2, is provided with a ridgelike projection26 along the periphery of end surface 7a for effecting oiltight contactwith the mouth 13 of blank D when the projection 26 is forced into themouth 13. FIG. 10 shows an example of the product C, obtained by usingthis type of piston, which has a cylindrical main portion 27 provided inopposite sides with reinforcing ribs 25 serving also as valve guides asaforementioned, with reinforcing ribs 29 further being formed atjunctions of the main body 27 and joints 28. The reinforcing rib 29,serving as a space for inserting a seat ring as already described, isformed by the hydraulic bulge forming carried out subsequently topreworking. The reinforcing ribs 25, if they are not formed bypreliminary working, are provided by hydraulic bulge forming afterpreworking.

I claim:

1. An apparatus for producing a valve body from a tubular blank'havingan open end and a closed end, comprising an upper die and a lower die,each die having a surface adapted to be brought into engagement when thedies are together, each die having a blank gripping portion, with saidgripping portions coacting, when the dies are together, to provide ahorizontal passage extending entirely through the dies, each die beingprovided at its center portion with a'bulging hole disposed at a rightangle with respect to the blank gripping portion, said holes being inregistry and in communication with the horizontal passage when the diesare together, a clamp press for clamping the upper and lower diestogether provided with a stopper piston inserted into each bulging hole,a pressing piston extending into the horizontal passage from eachopposite end thereof for movement relative to each other, one of saidpressing pistons having an end portion provided with an oil inlet and anoil outlet, the other of said pressing pistons having an end portioncorresponding in form to the bottom of a body to be produced, the endportion of said one piston having a surface engaging the edge of theopen end of the tubular blank positioned in the passage between saidpressing pistons for effecting an oil seal between said one pressingpiston and the tubular blank, and the arrangement being such that uponthe pressing pistons being moved towards each other, the end portion ofsaid one pressing piston engages the edge of the open end of the blankand the end portion of said other pressing piston engages the closed endof the blank, with introduction of pressure oil through the oil inlet ofsaid one pressing piston into the interior of the blank urging the blankinto said bulging holes until blocked by the stopper pistons while theblank is being compressed by said pressing pistons, with the closed endof the blank being deformed to the form of the end portion of said otherpressing piston.

2. The apparatus for forming a valve body from a tubular blank asclaimed in claim 1 wherein a groove is provided along the surface ofeach of said upper and lower dies for forming a rib in the blank servingas a reinforcement and a valve guide.

3. The apparatus for forming a valve body from a tubular blank asclaimed in claim 1 wherein an annular groove for forming a reinforcingrib is provided along the edge of said bulging hole in said blankgripping portion of each of said upper and lower dies.

4. The apparatus for forming a valve body from a tubular blank asclaimed in claim 1 wherein a groove is provided along the surface ofeach of said upper and lower dies for forming a rib in the blank servingas a reinforcement and a valve guide and an annular groove for forming areinforcing rib provided along the edge of said bulging hole in saidblank gripping portion of each of said upper and lower dies.

5. The apparatus for forming a valve body from a tubular blank asclaimed in claim 1 wherein a cavity for forming a seat for fixing a cockis provided in said other piston at its end portion.

6. The apparatus for forming a valve body from a tubular blank asclaimed in claim 1 wherein said end portion of said other pressingpiston is provided in a distance piece detachably attached to the end ofsaid other pressing piston.

7. The apparatus for forming a valve body from a tubular blank asclaimed in claim 1 including means for advancing both of said pressingpistons at the same velocity in operative relationship with each other.

8. A method for forming a valve body from a tubular blank having an openend and a closed end comprising placing the tubular blank in a passagebetween an upper die and a lower die, with each of said upper and lowerdies being provided with a blank gripping portion coacting to definesaid passage; forming a bulging hole in the center of each of said diesat a right angle to the gripping portion with each hole communicatingwith the passage; bringing a pressing piston inserted into one end ofthe passage into oiltight contact with the open end of the blank;introducing pressure oil into the blank through said pressing piston sothat, while the blank is being compressed at opposite sides thereof bysaid pressing piston and a second pressing piston inserted into saidpassage at the other end thereof, the blank is bulged to the shapedefined by said passage, the end surface of said second-pressing piston,said bulging holes and stopper pistons inserted into said bulging holes;and cutting off portions of the formed body which are bulged into saidbulging holes. 7

9. A method for forming a valve body from a tubular blank having an openend and a closed end comprising placing the tubular blank in a passagebetween an upper die and a lower die, with each of said upper and lowerdies being provided with a blank gripping portion coacting to definesaid passage; forming a bulging hole in the center of each of dies at aright angle to the gripping portion, with each hole communicating withthe passage; deforming the blank to the shape in section of said passageby compressing the blank with said dies; sealing the open end of theblank in an oil-tight manner by advancing separate pressing pistonsinserted into said passage at the opposite ends thereof; introducingpressure oil into the blank through one of said pressing pistons so asto bulge the blank to such an extent that the blank is blocked bystopper pistons respectively disposed in said bulging holeswhile theblank is being compressed by said pressing pistons advanced at the samevelocity in operative relationship with each other, with the closed endof the blank thereby being deformed to the shape of the end surface ofsaid pressing piston in contact with the closed end; and cutting offportions of the formed body which are bulged into said bulging holes.

1. An apparatus for producing a valve body from a tubular blank havingan open end and a closed end, comprising an upper die and a lower die,each die having a surface adapted to be brought into engagement when thedies are together, each die having a blank gripping portion, with saidgripping portions coacting, when the dies are together, to provide ahorizontal passage extending entirely through the dies, each die beingprovided at its center portion with a bulging hole disposed at a rightangle with respect to the blank gripping portion, said holes being inregistry and in communication with the horizontal passage when the diesare together, a clamp press for clamping the upper and lower diestogether provided with a stopper piston inserted into each bulging hole,a pressing piston extending into the horizontal passage from eachopposite end thereof for movement relative to each other, one of saidpressing pistons having an end portion provided with an oil inlet and anoil outlet, the other of said pressing pistons haVing an end portioncorresponding in form to the bottom of a body to be produced, the endportion of said one piston having a surface engaging the edge of theopen end of the tubular blank positioned in the passage between saidpressing pistons for effecting an oil seal between said one pressingpiston and the tubular blank, and the arrangement being such that uponthe pressing pistons being moved towards each other, the end portion ofsaid one pressing piston engages the edge of the open end of the blankand the end portion of said other pressing piston engages the closed endof the blank, with introduction of pressure oil through the oil inlet ofsaid one pressing piston into the interior of the blank urging the blankinto said bulging holes until blocked by the stopper pistons while theblank is being compressed by said pressing pistons, with the closed endof the blank being deformed to the form of the end portion of said otherpressing piston.
 2. The apparatus for forming a valve body from atubular blank as claimed in claim 1 wherein a groove is provided alongthe surface of each of said upper and lower dies for forming a rib inthe blank serving as a reinforcement and a valve guide.
 3. The apparatusfor forming a valve body from a tubular blank as claimed in claim 1wherein an annular groove for forming a reinforcing rib is providedalong the edge of said bulging hole in said blank gripping portion ofeach of said upper and lower dies.
 4. The apparatus for forming a valvebody from a tubular blank as claimed in claim 1 wherein a groove isprovided along the surface of each of said upper and lower dies forforming a rib in the blank serving as a reinforcement and a valve guideand an annular groove for forming a reinforcing rib provided along theedge of said bulging hole in said blank gripping portion of each of saidupper and lower dies.
 5. The apparatus for forming a valve body from atubular blank as claimed in claim 1 wherein a cavity for forming a seatfor fixing a cock is provided in said other piston at its end portion.6. The apparatus for forming a valve body from a tubular blank asclaimed in claim 1 wherein said end portion of said other pressingpiston is provided in a distance piece detachably attached to the end ofsaid other pressing piston.
 7. The apparatus for forming a valve bodyfrom a tubular blank as claimed in claim 1 including means for advancingboth of said pressing pistons at the same velocity in operativerelationship with each other.
 8. A method for forming a valve body froma tubular blank having an open end and a closed end comprising placingthe tubular blank in a passage between an upper die and a lower die,with each of said upper and lower dies being provided with a blankgripping portion coacting to define said passage; forming a bulging holein the center of each of said dies at a right angle to the grippingportion with each hole communicating with the passage; bringing apressing piston inserted into one end of the passage into oiltightcontact with the open end of the blank; introducing pressure oil intothe blank through said pressing piston so that, while the blank is beingcompressed at opposite sides thereof by said pressing piston and asecond pressing piston inserted into said passage at the other endthereof, the blank is bulged to the shape defined by said passage, theend surface of said second-pressing piston, said bulging holes andstopper pistons inserted into said bulging holes; and cutting offportions of the formed body which are bulged into said bulging holes. 9.A method for forming a valve body from a tubular blank having an openend and a closed end comprising placing the tubular blank in a passagebetween an upper die and a lower die, with each of said upper and lowerdies being provided with a blank gripping portion coacting to definesaid passage; forming a bulging hole in the center of each of dies at aright angle to the gripping portion, with each hole communicating withthe passage; deforming the blanK to the shape in section of said passageby compressing the blank with said dies; sealing the open end of theblank in an oil-tight manner by advancing separate pressing pistonsinserted into said passage at the opposite ends thereof; introducingpressure oil into the blank through one of said pressing pistons so asto bulge the blank to such an extent that the blank is blocked bystopper pistons respectively disposed in said bulging holes while theblank is being compressed by said pressing pistons advanced at the samevelocity in operative relationship with each other, with the closed endof the blank thereby being deformed to the shape of the end surface ofsaid pressing piston in contact with the closed end; and cutting offportions of the formed body which are bulged into said bulging holes.